Kidlington has a moderate flood risk, and almost all of it comes from rain rather than rivers. The main river-flood zone misses the place entirely. About one postcode in eleven rates high on at least one flood measure. Fewer than two dozen homes are at medium or high risk from rivers. The Cherwell is the obvious worry, but it is the drains you should be asking about.
On the Environment Agency's river-and-sea flood zones, about 2% of the area's postcodes are in zone 2 and none at all are in zone 3. Zone 2 is the medium-probability band outside the highest-risk zone, so 2% is the whole of Kidlington's exposure on this map.
The surface-water picture is different. Water from heavy rain collects where the ground and the drains send it, which has little to do with where the river runs, and that accounts for most of the risk on the postcode measures below. A brook that once ran along Mill Street now runs underground into the Cherwell. Burying a stream moves it out of sight, and in a downpour the water still finds its way downhill.
The Environment Agency also models how the flood zones would spread with a climate-change allowance added, and on that version about 7% of postcodes fall inside. That shows how far the modelled zone grows under the allowance. It does not tell you when anything will flood.
For most Kidlington homes, flood risk should make little difference to buying insurance or to the premium. The few properties in the higher bands are a different matter: insurers price by individual address, and a house on a mapped surface-water route can be quoted noticeably more than the house next door. The Environment Agency's long-term flood risk service gives a separate result for rivers and for surface water at any address, and it takes about a minute to check the one you are thinking of buying.
The broadest measure covers every Kidlington postcode against several types of flooding, surface water included, and records its highest rating on any of them. On that basis, about 9% of postcodes rate high on at least one measure, 19% medium and 38% low. A postcode only needs one measure to flag it, so these shares run well above the zone figures.
Counting homes rather than postcodes makes the picture smaller. On the Environment Agency's rivers-and-sea mapping, 5 properties are at high risk, 17 at medium, 177 at low and 109 at very low. Those come from just 820 properties in 24 postcodes, because postcodes with no river or sea risk at all are left out of the count.
The question of defences barely comes up here. The Environment Agency's modelled flood extents put none of Kidlington's postcodes inside the high-probability area, with or without defences, and about 2% fall in the low-probability extent without defences. A defence appearing in the model would only mean one exists. It would say nothing about whether that defence would hold. Nine flood events are on record, and the latest, in July 2007, came from a main river overtopping its channel where there were no raised defences.
The nearest tide gauge is at Portsmouth, where sea level rose by about 2 millimetres a year between 1962 and 2023. Sea level is a south-coast problem, and Kidlington is a long way from the sea.
Kidlington sits in the middle for flood risk: the river zones barely reach it, but heavy rain affects enough postcodes that it pays to check the individual house.